Floyd DNA Project


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It is obvious from our observation of 1000's of samples that some markers change or mutate at a faster rate than others. While that actual 'faster rate' has not yet been definitively calculated, not all markers should be treated the same for evaluation purposes.
The markers in red have shown a faster mutation rate then the average, and therefore these markers are very helpful at splitting lineages into sub sets, or branches, within your family tree.
Explained another way, if you match exactly on all of the markers except for one or a few of the markers we have determined mutate more quickly, then despite the mutation this mismatch only slightly decreases the probability of two people in your surname group who match 11/12 or even 23/25 of not sharing a recent common ancestor. 
Interpreting genetic distance

What are the probabilities of matching?   More information

Table Shows # of Generations

Match  

50%

90%

95%

95% Confidence Interval
12-0 Match exactly at all 12 markers 

14

48

62

1-77
11-1 11 exact matches, 1 mismatch 

37

85

103

5-121
10-2 10 exact matches, 2 mismatch 

61

122

144

14-165
25-0 Match exactly at all 25 markers 

7

23

30

0-37
24-1 24 exact matches, 1 mismatch 

17

40

48

2-57
23-2 23 exact matches, 2 mismatch 

28

56

66

6-75
 

READING THE DNA TABLE

DNA - Deoxyribonucleic Acid:  the main constituent of chromosomes - the double helix containing the chemical code that defines who and what we are.
Allele Numbers:  Any of two or more genes that have the same relative position  on related chromosomes
Numbers are Repeats:  Each participant's allele repeats for their measured loci (DYS) in the following table.  Comparison of these results (numbers) is analogous to matching the scratches on bullets to determine which ones were fired from the same gun.

Why Some Rows Are Longer: - Most Recent Common Ancestor (MRCA)
Some participants took the 12 Marker test  - 14.4 generation MRCA
Some participants took the 25 Marker test   -  6.8 generations MRCA

UNDERSTANDING THE RESULTS OF A 12 MARKER TEST
UNDERSTANDING THE RESULTS OF A 25 MARKER TEST

The Y-chromosome signatures change very slowly over time and the pattern is usually stable over hundreds of years, but for some unknown and unexpected reason, a mutation can occur without notice in any generation.  Male relatives who have an uninterrupted male-male link between them will share the same, or very similar Y-chromosome signatures. The Y-line is particularly useful when a connection between different branches of a family is suspected but cannot be proven from written records.  Using the Y-line, by comparing the Y-chromosome signatures, provides the answer.A generation for genealogical purposes is usually considered to be 30 years, whereas a generation for DNA purposes is usually considered to be about 20-25 years.  Some of the reasons that can cause a Y-line to be a non-match with a participants' previous genealogical paper research and/or family tradition include incorrect paper genealogy research;  adoption;  rape; or infidelity.

RESULTS ANALYZED.

Of interest is a number called the MRCA time or the estimated time (in generations) to the occurrence of the Most Recent Common Ancestor between two people. Dr. Bruce Walsh of the University of Arizona has calculated this time to be 42 generations at a 50% confidence when the haplotype (repeat pattern) for two people match each other exactly, i.e. 12 markers out of 12. The haplotype for a person is simply the sequential listing of the recorded "repeats" that have been measured. Dr. Walsh's calculations also show this to be 69 generations at a 90% confidence and 93 generations at a 95% confidence. In most cases, however, the common ancestor will occur much sooner. It does suggest, however, the likelihood you share a recent common ancestor with another person diminishes very rapidly as you match fewer and fewer markers.

 

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